It should be B. The dash-line triangle is half the size of the solid-lined triangle. You can find the scale factor by finding the ratio between the side lengths of the two triangles. The scale factor in this case is 2 because you are reducing thr solid-lined triangle by one half. If you are reducing by a fraction, it means that you are enlarging be the reciprical of the fraction. As reducing implies division and dividing a fraction is equivalent to multiplying by the reciprical. Thus the correct answer is B.
